The following table illustrates unique characteristics that translate into system advantages and disadvantages.

Collision avoidance sensor summary. (Source: NHTSA)

V2V safety systems use messages broadcast by vehicles to enable cooperative crash warning applications. Compared to sensors, V2V systems offer a clear advantage for field-of-view and range, the NHTSA concludes. The NHTSA believes V2V is superior because it can detect and warn of threats from any direction using a single GPS sensor and DSRC communication.

The report, however, points out concerns over basic safety-message congestion issues.

Current research has shown that V2V safety applications perform reliably in test scenarios with up to 200 vehicles in communication range. However, research conducted by the NHTSA and others has yet to estimate "the number of other DSRC-equipped vehicles that a single DSRC radio would need to be exposed to in an environment (such as heavy freeway traffic) where channel congestion would be significant."

Vehicle-to-Vehicle technology is still on the development, but I suppose it has spread application future.

If the vehicles could communicate with each other by wireless system, the drivers are able to make the right operation in advance in order to avoid the danger happening. Therefore, it could decline the traffic addidents.

Bert, I agree with your comments. I would like to point out that not only Mercedes, but also, some of the major Japanese nameplates include similar capabilities in their current (2014) models, at least in the "luxury" brand SUVs. These as shown in the ads are COMPLETELY AUTOMATED and promoted as reacting so fast the driver may not even be aware of what is happening until the event is over! Those bayb=y steps you mentiuoned have already become strides, maybe even giant steps. I'm ambivalent about this and would not go looking for these features in my next car,, but given the sorry state of the average US driver's skills, on balance it will likely help a lot!

We're talking about a V2V communication system, which makes us think about the kind of interface we'll be using. Just like an android phone and an apple phone can communicate using communication channels, it wouldn't matter which party developed the interface, it would work via communication corridoos. The only question is what would be the bandwidth requirement and how many nodes (hence cars) can the network support.

What also causes accidents is the failure of drivers to see/heed the traffic lights. If the grids could be developed in such a way that the sensors near a traffic signal could trigger the smart car to slow down in a controlled manner, that could save many lives, but that would also mean we wouldn't get to see many high speed chases, but it will probably save live, so that is a given plus.

I believe , the crux of the matter , as far accidents are concerned , is speed.

If speed is controlled properly ( cruising as well as acceleration ) then majority of accident situations would not be existing.

So the major focus of this V2V system should be to control speed , with respect to the road condition, the vehicular traffic around the vehicle , the intersections etc.

If we leave out the word "hurry" from the driver's dictionary , we would not have that fear of possible accidents - at turning points, at entry and exits, at intersections and in adverse driving conditions.

So all that V2V systems have to control is speed so as to avoid accident situations.

So even if the V2V system recognises a possible accident situation, it does not have to slam the brakes and jolt the passengers from their slumber!

I wonder how the E-class makes the decision, and how easy it is to spoof?

That occurred to me too. However, the easy answer in the short term is, use the technology as a warning to the (obviously) moribund or otherwise distracted human driver. Driver assistance systems are not nearly as prone to risky scenarios as fully autonomous driving would be. Or let's be more accurate. ADAS is less prone to risks that we aren't already familiar with, than fully autonomous driving would be. Not more risks, but risks we haven't already taken for granted, in our primitive state of fully manual driving.

Karen asked: For example how we can in this day and age manage to crash two trains head-on traveling on the same track?

That's usually caused by technology, specifically by an operator texting or otherwise illegally using a mobile device instead of watching the track ahead and observing signals.

One can also argue that the accident is caused by LACK OF technology. Specifically, that a distracted/distractable human is being permitted to put a whole train at risk.

Today I avoided an accident that V2V would have been perfect at preventing. Driving down a street, hulking long truck parked on the right, just before an intersection. Distracted human driver approaches the street I'm on, from the perpendicular side street, on my right. So, approach the intersection, and even though she obviously couldn't see the oncoming traffic from the main street, due to this hulking parked truck, she finds it perfectly acceptable to barge on through and turn to her left (i.e. broadside in front of me).

LIDAR, radar, human eyeballs, none of that works in this case. We're at the mercy of the other driver's attention and skill. But V2V would have given me and the other driver a warning that someone was moving that we couldn't see, coming right in our respective paths.

And yes, of course, V2V requires interoperable standards, as would V2I, where local sensors don't. Much as communicating with other people requires an interoperable standard, called "language" (not to mention vocal cords and ears that operate at the same frequencies). Where using your eyes does not.

I wouldn't expect the NHTSA to work out those details, but rather some other organization like the IEEE. V2V sounds like an application of ad-hoc networking. It would help if vehicles could relay comms from other vehicles, within close range but obstructed by buildings or big, hulking trucks.

mhrackin wrote: Surely you've seen the Mercedes commercial for the E-class with the ability to slam on the brakes when the car decides it's necessary to avoid an accident...

I'm afraid you have vastly overestimated the amount of time Betajet spends watching TV :-)

I wonder how the E-class makes the decision, and how easy it is to spoof? At what point do bored teen-agers with nothing better to do drop fire crackers and tires off overpasses in front of "smart" cars to watch them slam on the brakes and maim their occupants? "Trolling for Taillights" (circa 1992) is fairly harmless and only targets speeders, but triggering sudden braking could really hurt people.

Addendum: Toyota and others seem to have enough trouble just detecting throttle position reliably. And now the auto industry and USA government expect us to believe they can do something vastly more complex even more reliably?

Surely you've seen the Mercedes commercial for the E-class with the ability to slam on the brakes when the car decides it's necessary to avoid an accident... no Government edict (or infrastructure- ignored in the report) required!